It is known that doors of vehicles represent vulnerable, or structurally weak, parts of such vehicles in potential impact or crash situations. Whereas a front portion of a vehicle, for example accommodating an engine, can be strengthened with various strengthening sills, space to accommodate strengthening features for vehicle doors is much more restricted. Of particular concern is to try to prevent doors of vehicles springing open or being pushed into the vehicles in impact situations, thereby potentially injuring occupants of the vehicles, while still allowing for the doors to be capable of being opened or removed, for example to gain access to the occupants immediately following accidents.
Various approaches have been proposed for strengthening doors of vehicles. For example, in a published German patent specification no. DE4133248, there is described a side crash protection system for a two-door passenger vehicle. The protection system comprises a three-part strip of metal and plastics material which extends, in operation, along front, door and tail sections of the vehicle. Joints are provided to two points to allow doors of the vehicle to open and close. Moreover, the protective strip can be extended to fit four door cars. Furthermore, the side crash protection system is alleged to be suitable for both old and new vehicles.
In another approach as described in a published United States patent application no. US2003/0025353, there is described a side impact support for incorporation into a door of a motor vehicle. The side impact support has a longitudinal profile with end portion towards the door column. Moreover, the impact support is configured asymmetrically with respect to its center transverse plane and has a reinforcement in a portion thereof corresponding to a sitting position of a passenger in the vehicle.
In the case of open-top vehicles, for example sports cars and cabriolets, doors and door surrounding members of such vehicles do not benefit from mechanical strength imparted by way of any vehicle roof structures. It is therefore necessary for the doors of such vehicles to be especially strong in order to withstand impacts, namely both front/rear impacts as well as lateral impacts. Whereas it is known to reinforce vehicle doors by including strengthening members therein, such measures are not in practice found to be entirely sufficient for providing desirable vehicle occupant safety. There arises therefore a technical problem of providing an improved approach to strengthening vehicle doors, and their associated surrounds.